Aerosol dispensing nozzle



Aug. 8, 1950 R. A. FULTON ETAL AEROSOL DISPENSING NOZZLE Filed July 8,1947 INVENTOR5. RA. FULTON/W0 J. H. FALES 14 7' TORNEY PatentedAug. 8,1950 AEROSOL DISPENSING NOZZLE Robert A. Fulton and John H. Fales,Silver Spring, I

Md.; dedicated to the free use of the People in the territory of theUnited States Application July 8, 1947, Serial No. 759,681

(Granted under the m of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 2 Claims.

This application is made under the act of March 3, 1883, as amended bythe act of April 30, 1928, and the invention herein described andclaimed, it patented, may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment to us of any royalty thereon.

We hereby dedicate the invention herein described to the free use of thepeople in the territory of the United States to take efi'ect on thegranting of a .patent to us.

This invention relates to the production of aerosols and is moreparticularly concerned with devices used to produce aerosols by theliquefied gas propellant method. See United States Patent No. 2,321,023.

In accordance with the liquefied gas propellant method, the material tobe dispersed as an aerosol is dissolved in a liquefied gas underpressure and the solution sprayed into the air. The liquefied gas boilsviolently, thereby breaking up the spray droplets into even smallerdroplets with the result that when evaporation is completed, thematerial remains suspended in the air in very mi. nute particles on theorder of a colloidal suspension.

In using this method as heretofore practiced, it is important to utilizelow boiling point gas propellants which, when liquefied, have relativelyhigh vapor pressures on th order of 50 to 100 pounds per square inch.Such pressures require the use of specially constructed containers. 'Thecost of these containers is very high relative to the cost of theircontents. Consequently, the ultimate consumer fails to obtain full valuefor the price he pays for such an aerosol producing solution when hepurchases it in such expensive containers. Moreover, it is difllcult tohandle liquefied gas solutions at such high pressures. This difiicultyinvolves additional increases in the cost of manufacture.

To obviate these deficiencies, attempts have been made to employ lowerpressure propellants, thereby permitting the use of inexpensivecontainers, such as ordinary beer cans, which cost only a fraction ofthat of the regular aerosol containers. However, the use of ordinaryspray devices is insuflicient to create a satisfactory aerothe provisionof a spray nozzle for the purpose indicated whichcan be used to createaerosols from solutions of propellants having very low vapor. pressuresand which are substantially as efiective as aerosols created by the useof ordinary propellants having vapor pressures of 60 to pounds persquare inch. 0

In general, the objects-oi this invention are attained by the provisionof a nozzle having two aligned apertures separated by a chamber whichpermits a preliminary expansion of the propellant before it is finallydischarged into the atmosphere. In particular, the nozzle comprises atubular member having a discharge end and another end adapted to beattached to the outlet of a container, this tubular member having achamber section. There are further provided axially disposed walls atthe ends of the chamber section, which walls have aperturestherethrough, the apertures through the wall at the discharge end beinlarger than the other aperture, the areas of these respective aperturesbeing in the approximate ratio of 3 to 2. The diameter of the aperturein the wall at the discharge end is in the range of 0.016 to 0.024 inch,while the diameter of the other aperture is in the range of 0.0135'to0.020 inch.

Two embodiments of this invention are illustrated in the accompanyingdrawing, in which Fig. 1 is an elevational view of an adjustableembodiment with a quarter section cut away:

Fig. 2 is also an elevational view with a quarter section cut away of afixed embodiment; and Fig. 3 is a vertical section of the upper part ofthe tubular nozzle member of Fig. 1 illustrating the relative sizes ofthe apertures in the walls thereof.

Referring with more .particularity to Fig. l, the embodiment illustratedcomprises a series oftubular members l5, l6, and 26. The tubular member15 is provided with threads I3 at its lower end that engagecorresponding threads of a head piece H, the latter bein integral withthe container ID in which the aerosol solution is disposed. The usualdip tube I2 is connected to the tubular member l5 and extends to thebottom (not shown) of the container.

The tubular member l6 comprises a lower section in the form of a hollowneedle I! that fits within the top part of the member l5 and isthreadedly engaged therewith. The connection is pressure-sealed by meansof a gasket 23 secured in position by means of a cap22 on threads M.

The objects of the present invention include 66 The bottom 0! the needleis closedand is prowardly from the wall of the member it. When theneedle is seated in this position on the shoulder 9, the contents of thecontainer it are sealed. The tubular member II is provided with thumbgrips 24 to facilitate turning it. When turned in one direction, thebeveled edge I 8 is forced against the shoulder 9. when turned in theopposite direction, it is moved out of contact with the shoulder,thereby permitting the passage of liquid within the container past this,point into an annular space It between the lower section oi the needleand the inner wall of the member II. From this point it passes inwardlythrough radial apertures l9 and 20 and then into the hollow core of theneedle, from whence it passes into the upper chamber 25 of the memberIS. The tubular member 26 is engaged with the exterior of the uppersection of the member l6 by means of threads 21.

The member 26 contains two removable walls 29 and 3|, one above theother, separated by a removable hollow cylinder 30 which cylindercomprises the expansion chamber. The walls, which are axially disposedat the ends of the cylinder, are provided with a central aperture 34having a diameter in the range of 0.0135 to 0.020 inch, and anothercentral aperture 35 having a diameter in the range of 0.016 to 0.024inch. Aperture 35, which is in the wall at the discharge end, is largerthan aperture 34, the areas of these respective apertures being in theapproximate ratio of 3 to 2. The liquid under pressure passes from theupper chamber 25 through the first aperture 34 and then into theexpansion chamber 30 where a small pressure drop is effected, withpartial boiling of the propellant. This results in part of thepropellant being converted to a gaseous phase and the formation ofdroplets of the remaining portion of the solution.

The residual pressure forces these droplets out through the aperture 35where the final pressure drop causes further boiling oi the liquefiedgas propellant in -each droplet, thereby causing the droplets to breakup into still finer particles which assume aerosol or near aerosolproportions when all the liquefied gas evaporates.

The walls 29 and 3|, together with the expansion chamber 30, are held inplace by means of a cap 32 removably engaged with the top of the member26 by means of threads 28. The cap is provided with a wide outwardlyflared passage 33 to permit escape of the material from the aperture 35and to guide it into a conicallike pattern.

In operation, it is important that the pressure drop eilfected in theexpansion chamber 30 be not too great but still great enough to obtainthe desired effect explained above. A pressure drop just suflicient toform the droplets without waste ing or expending any unnecessary energyrepresented by the liquefied gas is important so as to reserve as muchof this energy as possible for the final pressure drop into theatmosphere where a breaking up of the droplets must take place. Thiscondition is a function of the size of the apertures 34 and 35. If theapertures are too large, the desired effects will not be obtained.Instead, only a wet mist will result.

Under the conditions of aperture sizes set forth above, we have foundthat a satisfactory volume of the expansion chamber is 0.008 to 0.01cubic inch, although it is not indispensable that the volume berestricted to this range. In general,

4 I I what is desired is the establishment of conditions which willprovide for a proper pressure drop in accordance with the requirementsset forth.

. These requirements may be translated into specihe pressure drops forspecific initial pressures which have been determined empirically to beas follows, all values being in pounds per square inch:

Initial Pressure to to to The arrangement of the aperture walls 29 and3| and the intervenin expansion chamber is such that they may be removedand substituted with chambers and walls having, apertures 01 diiferentsizes to suit any particular conditions. Such substitution may beeffected by removing the cap 32, then the walls 29 and ii with expansionchamber 30, reinserting other combinations of walls and expansionchambers having the desired dimensions and replacing the cap 32.

However, when such flexibility is not necessary and it is suilicient toemploy a nozzle having fixed dimensions, the embodiment of Fig. 2 may beemployed. In this embodiment all parts are fixed or integral. Thethreads 46 at the base of the nozzle are adapted to fit the threads 21on the tubular member IS. The tip ll of the nozzle is provided with anaperture 43. Between the tip 4| and the base of the home, a partition 42is provided having an aperture 44. The space 45 between the tip II andthe partition 42 constitutes the expansion chamber. The size of theexpansion chamber and of the apertures 43 and 44 conform, of course, tothe requirements set forth above in order to obtain satisfactoryaerosols and to avoid dripping onseparatory action of the aerosol. Theinner wall 41 of the section between the base of the nozzle and thepartition 42 is preferably streamlined to avoid any unnecessary heatlosses through eddy currents.

Although this invention has been described as being particularly usefulfor use in dispensing aerosol solutions of low vapor pressure, it is tobe understood that it may also be used for dispensing aerosol solutionsof high vapor pressure. Havin thus described our invention, we claim: 1.An aerosol dispensin nozzle comprising a tubular member having adischarge end and another end adapted to be attached to the outlet of acontainer, said member having a chamber section, axially disposed wallsat the ends of the chamber section, said walls having aperturestherethrough, the diameter of the aperture in the 7 wall at thedischarge end being in the range of 0.016 to 0.024 inch and the diameterof the other aperture being in the range of 0.0135 to 0.020 inch, thearea of said aperture through the wall at the discharge end being to thearea of the other aperture in the approximate ratio of 3 to 2.

2. An aerosol dispensing nozzle comprising a tubular member having adischarge end and another end adapted to be attached to the outlet of acontainer, said member having a chamber section, a removable cylinder insaid chamber section having a volume in the range of 0.008 to 0.01 cubicinch, axially disposed removable walls at the ends of the cylinder, saidwalls having each an aperture therethrough, the diameter of 8 theaperture in the wall at the discharge end being in the range of 0.016 to0.024 inch and the diameter of the other aperture being in the range of0.0135 to 0.020 inch, the area. of said aperture through the wall at thedischarge end being to 5 the area of the other aperture in theapproximate ratio of 3 to 2.

ROBERT A. FULTON.

JOHN H. FALES.

REFERENCES CITED 0 UNITED STATES PATENTS Number Name Date Palmer Mar.22, 1887 Battelle Dec. 27, 1904 Green Nov. 29, 1910 Koerting July 25,1916 Rotheim Jan. 3, 1933 Vensel June 19, 1945 Gebauer et al May 14,1946

